Abstract

The main focus of this paper is the applications of polymer treatment in controlling injectivity profiles and the improvement of the conformance of the near-wellbore injection profiles. Reservoir high permeability zones causing distortions of water injection profiles at the wellbore, and the possible existence of layer barriers were identified using conventional investigation tools such as Open Hole Logs, Production Logging Tools, Formation Micro Scanners.

A polymer screening procedure was put in place so that appropriate polymer formulations for use as agents for reducing fluid mobility in the high permeability zones at the wellbore can be identified. The use of these polymer formulations facilitated the improvement of near-wellbore conformance of injectivity profiles.

The success or failure of field application or the polymer treatment program was ascertained by using a monitoring program which combined the application of the Production Logging Tools with well test analyses.

Introduction

The presence of high permeability streaks and fractures is a common occurrence in stratified carbonate reservoirs. If these reservoirs are subjected to patterned waterflooding operations, it is not uncommon for the highly permeable zones to accept most if not all of the water injected. This tends to distort the injectivity profile at the wellbore and raises the possibility of an eventual poor reservoir coverage and sweep efficiency. Therefore, a successful water-flood project necessarily demands a clear understanding of reservoir characteristics with a view to identifying the incidence of high permeability streaks, channels, and layer barriers so that adequate remedial actions that can reduce their adverse effects of water-flood performance can be put in place. One of such remedial actions which have gained prominence in the recent past, is the use of Polymer1,2,3 and Non-polymer4,5 agent in injection/Production wellbore profile modification.

In this paper, we present the screening, monitoring and evaluation procedures for a successful application of a cross-linked polymer formulation on water injection wells in order to improve the wellbore conformance of injectivity profiles.

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